Institution: | (1) Department of Mathematics, Quaid-i-Azam University, 45320 Islamabad, Pakistan;(2) School of Computational & Applied Mathematics, Centre for Differential Equations, Continuum Mechanics and Applications, University of the Witwatersrand, Wits, 2050 Johannesburg, South Africa;(3) COMSATS, Institute of Information and Technology, Abbottabad, Pakistan;(4) Pennsylvania State University, York Campus, York, PA, 17403, U.S.A. |